1. Field of the Invention
The present invention relates to an improvement of a waterproof control unit, which is an on-vehicle electronic control device to be mounted in, for example, an engine compartment, and also relates to an improvement of a method of assembling the waterproof control unit.
2. Description of the Related Art
There have been widely used waterproof control units including a casing including a base and a cover and a circuit board hermetically housed in the casing, onto which a circuit component and a plurality of external connection contact terminals are mounted, and a connector housing made of a resin forming material is positioned and fixed, in which, in order to expose, from the casing, an end surface of the connector housing having the plurality of contact terminals passing therethrough, waterproof sealing materials filled into a first sealing gap defined between abutment surfaces of the connector housing and the cover, a second sealing gap defined between abutment surfaces of the connector housing and the base, and a third sealing gap defined between abutment surfaces of the base and the cover, respectively, are provided.
Further, as waterproof sealing surfaces, for example, there has been widely used a convexoconcave sealing surface system including convex-concave-convex threads formed in an outer peripheral contour portion of the cover, concave-convex-concave threads formed in an outer peripheral contour portion of the base, and a waterproof sealing material filled into a convexoconcave sealing gap defined by loosely fitting the convex thread on one side into the concave thread on the other side. In this case, as sealing surfaces of the connector housing interposed between the cover and the base, it is necessary to form the concave-convex-concave threads on the cover side, and to form the convex-concave-convex threads on the base side. Therefore, it is necessary to provide two types of convexoconcave sealing surfaces in the connector housing.
The first feature of the convexoconcave sealing surface system is that a long water sealing distance (sealing path) is secured even when the sealing width is small. The second feature of the convexoconcave sealing surface system is that, even when one convex thread wall surface abuts on one concave thread wall surface due to an assembly dimension error between the cover and the base so that the film thickness of the waterproof sealing material becomes zero, the waterproof sealing material is filled in a gap between the other convex thread wall surface and the other concave thread wall surface, and hence a predetermined amount of the waterproof sealing material is securely filled between the wall surfaces on any side.
On the other hand, the first drawback of the convexoconcave sealing surface system is as follows. That is, it is necessary to provide two types of convexoconcave sealing surfaces in the connector housing as described above, and hence the connector housing has a long body dimension and a plurality of contact terminals press-fitted to the connector housing also have a long dimension. Therefore, it is necessary to take measures so as to prevent increase in electric resistance.
The second drawback of the convexoconcave sealing surface system is that an apparent thickness dimension between the sealing surfaces becomes larger so as to secure a fitting depth of the convexoconcave surfaces. The third drawback of the convexoconcave sealing surface system is as follows. That is, when the cover is formed by, for example, sheet metal working, it is difficult to forma narrow, deep, and precise convexoconcave surface. Even when the cover is formed of resin, from the viewpoint of the life of a die, it is impossible to form an extremely narrow and deep convexoconcave surface. Thus, there is a limitation on downsizing to be expected. When the load on the die is to be reduced, the connector housing may have a long body.
For example, referring to FIGS. 1 and 3 of an “electronic device” disclosed in Japanese Patent Application Laid-open No. 2009-070855, a printed circuit board 40 having a connector mounted thereonto is housed in a casing of the electronic device and an inner space of the casing is waterproofed. In an upper case 20 (corresponding to the cover) and a lower case 30 (corresponding to the base) of the casing, as a sealing part that comes in contact with a sealing member, a second recess part 35b is formed in one open side portion, and a second protruding part 25b is formed in the other open side portion. At a surface portion of a housing 51 that faces the open side portions, as a looped sealing part that comes in contact with the sealing member, a connector-side protruding portion 54 to be inserted into the second recess part 35b under a state in which the sealing member is arranged therein and a connector-side recess portion 53 into which the second protruding part 25b is to be inserted under a state in which the sealing member is arranged therein are formed continuously.
Thus, the width of the connector-side recess portion 53 is equal to the sum of a width corresponding to the widths of two other recess portions and a width corresponding to the width of one connector-side protruding portion 54, and hence the width of the connector-side recess portion 53 is a dimension that is three times as large as the width of the other recess portion. As illustrated in FIG. 1, the recess portions on both sides of the connector-side protruding portion 54 communicate to the connector-side recess portion 53, and hence there is a feature in that continuity is secured when the waterproof sealing material is to be applied.
Further, the sealing surfaces of the housing 51 and the upper case 20 and the sealing surfaces of the housing 51 and the lower case 30 are arranged, in a unified manner, on an outer surface of a partition wall of a connector 50 to which connector terminals are press-fitted. The widths of the protruding portions and the recess portions are limited so that a dimension corresponding to the sum of a press-fitting dimension of each of the connector terminals and a contact dimension of each of the connector terminals with those of a mating connector is minimized and thus the connector terminals do not have a long dimension.
Referring to FIGS. 1 and 3 of an “electronic control apparatus” disclosed in Japanese Patent Application Laid-open No. 2009-123558, sealing materials 130 are applied to an interface between an outer side of a top casing 50 (corresponding to the cover) and an outer edge of a bottom casing 70 (corresponding to the base), which form a casing body of an electronic control apparatus 10, an interface between a housing 111 of a connector 110 mounted on a circuit board 90 and the outer edge of the top casing 50, and to an interface between the housing 111 and the outer edge of the bottom casing 70, respectively, and an inner space of the casing body that houses the circuit board 90 is water-sealed. A top sealing projection 57 formed on the top casing 50 and a top sealing recess 119 formed in the housing 111 mate with each other. Sealing surfaces of the top sealing projection 57 and the top sealing recess 119 are provided on an inner side of a partition wall of the housing 111. A bottom sealing recess 77 formed on the bottom casing 70 and a bottom sealing projection 120a formed in the housing 111 mate with each other. Sealing surfaces of the bottom sealing recess 77 and the bottom sealing projection 120a are provided on an outer side of the partition wall of the housing 111.
As described above, the sealing surfaces of the housing 111 and the top casing 50 and the sealing surfaces of the housing 111 and the bottom casing 70 are separated into an inner surface and an outer surface of the partition wall of the connector 110 to which connector terminals are press-fitted. The widths of the projections and the recesses are limited so that a dimension corresponding to the sum of a press-fitting dimension of each of the connector terminals and a contact dimension of each of the connector terminals with those of a mating connector is minimized and thus the connector terminals do not have a long dimension.
Referring to FIG. 3 of a “board housing case for vehicle-mounted electronic device” disclosed in Japanese Patent Application Laid-open No. 2013-004611, a circuit board 40 is hermetically-sealed and housed in a metal case formed of a metal base 30 and a metal cover 20. A concave thread formed in the cover 20 is fitted onto a convex thread formed on a connector housing 41. Convexoconcave sealing surfaces are provided on an inner side of a partition wall of the connector housing 41. A convex thread formed on the base 30 is fitted into a concave thread formed in the connector housing 41. Convexoconcave sealing surfaces are also provided on the inner side of the partition wall of the connector housing 41. However, the two types of convexoconcave sealing surfaces provided on the connector housing 41 are arranged while being shifted from each other, and hence the connector housing has a long body dimension.
As described above, in each of Japanese Patent Application Laid-open Nos. 2009-070855, 2009-123558, and 2013-004611, it is necessary to provide two types of convexoconcave sealing surfaces in the connector housing, and hence the connector housing has a long body dimension. However, it is necessary to cause the two types of convexoconcave sealing surfaces to communicate to each other with the waterproof sealing material, and in Japanese Patent Application Laid-open Nos. 2009-123558 and 2013-004611, the two types of convexoconcave sealing surfaces are connected to a common accumulation portion for the waterproof sealing material.
In the “electronic device” disclosed in Japanese Patent Application Laid-open No. 2009-070855, the convex-concave-convex sealing surface provided on the housing 51, on which the connector-side recess portion 53 to be fitted onto the second protruding part 25b of the upper case 20 is formed at the center, and the concave-convex-concave sealing surface provided on the housing 51, on which the connector-side protruding portion 54 to be fitted into the second recess part 35b of the lower case 30 is formed at the center, pass by and merge with each other at an intermediate portion of the side surface of the housing 51.
Thus, both of the connector opening portion of the upper case 20 and the connector opening portion of the lower case 30 are raised up to the intermediate position on the side surface of the connector. Therefore, when the lower case 30 is formed by, for example, aluminum die casting and the upper case 20 is formed of, for example, a resin forming material, there is a problem in that the entire weight becomes larger.
Further, in the “electronic control apparatus” disclosed in Japanese Patent Application Laid-open No. 2009-123558, the convex-concave-convex sealing surface provided on the housing 111, on which the top sealing recess 119 to be fitted onto the top sealing projection 57 of the top casing 50 is formed at the center, and the concave-convex-concave sealing surface provided on the housing 111, on which the bottom sealing projection 120a to be fitted into the bottom sealing recess 77 of the bottom casing 70 is formed at the center, are arranged across the partition wall of the housing 111.
Thus, the bottom casing 70 is extended beyond the partition wall of the housing 111. Therefore, when the bottom casing 70 is formed by, for example, aluminum die casting and the top casing 50 is formed of, for example, a resin forming material, there is a problem in that the entire weight becomes larger.
Still further, in the “board housing case for vehicle-mounted electronic device” disclosed in Japanese Patent Application Laid-open No. 2013-004611, the concave-convex-concave sealing surface provided on the connector housing 41, on which the convex thread on the connector housing side to be fitted into the concave thread of the cover 20 is formed at the center, and the convex-concave-convex sealing surface provided on the connector housing 41, on which the concave thread on the connector housing side to be fitted onto the convex thread of the base 30 is formed at the center, pass by and merge with each other at both end positions on the base 30 in a longitudinal direction of the connector housing 41. Therefore, there is a problem in that the connector has a long body.
Still further, the cover 20 and the base 30 are formed by sheet metal working, and the convexoconcave sealing surfaces pressed into an undulating shape are shallow and wide. Therefore, there is a problem in that the connector has an even longer body and the electric resistance of the connector pins is increased, resulting in a factor of heat generation. Note that, even when the cover is formed into a resin forming product and the base is formed by aluminum die casting, there are problems in that it is difficult to manufacture the die for narrow and deep convexoconcave sealing surfaces, that the releasability becomes poor, and that the life of the die becomes shorter. The same problems are also inherent in Japanese Patent Application Laid-open Nos. 2009-070855 and 2009-123558.